// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.

use std::sync::Arc;

use crate::web_worker::WebWorkerInternalHandle;
use crate::web_worker::WebWorkerType;
use deno_core::error::type_error;
use deno_core::error::AnyError;
use deno_core::op2;
use deno_core::url::Url;
use deno_core::OpState;
use deno_fetch::data_url::DataUrl;
use deno_web::BlobStore;
use deno_websocket::DomExceptionNetworkError;
use hyper::body::Bytes;
use serde::Deserialize;
use serde::Serialize;
use tokio::task::JoinHandle;

// TODO(andreubotella) Properly parse the MIME type
fn mime_type_essence(mime_type: &str) -> String {
  let essence = match mime_type.split_once(';') {
    Some((essence, _)) => essence,
    None => mime_type,
  };
  essence.trim().to_ascii_lowercase()
}

#[derive(Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct SyncFetchScript {
  url: String,
  script: String,
}

#[op2]
#[serde]
pub fn op_worker_sync_fetch(
  state: &mut OpState,
  #[serde] scripts: Vec<String>,
  mut loose_mime_checks: bool,
) -> Result<Vec<SyncFetchScript>, AnyError> {
  let handle = state.borrow::<WebWorkerInternalHandle>().clone();
  assert_eq!(handle.worker_type, WebWorkerType::Classic);

  let client = deno_fetch::get_or_create_client_from_state(state)?;

  // TODO(andreubotella) It's not good to throw an exception related to blob
  // URLs when none of the script URLs use the blob scheme.
  // Also, in which contexts are blob URLs not supported?
  let blob_store = state
    .try_borrow::<Arc<BlobStore>>()
    .ok_or_else(|| type_error("Blob URLs are not supported in this context."))?
    .clone();

  // TODO(andreubotella): make the below thread into a resource that can be
  // re-used. This would allow parallel fetching of multiple scripts.

  let thread = std::thread::spawn(move || {
    let runtime = tokio::runtime::Builder::new_current_thread()
      .enable_io()
      .enable_time()
      .build()?;

    let handles: Vec<_> = scripts
      .into_iter()
      .map(|script| -> JoinHandle<Result<SyncFetchScript, AnyError>> {
        let client = client.clone();
        let blob_store = blob_store.clone();
        runtime.spawn(async move {
          let script_url = Url::parse(&script)
            .map_err(|_| type_error("Invalid script URL"))?;

          let (body, mime_type, res_url) = match script_url.scheme() {
            "http" | "https" => {
              let resp =
                client.get(script_url).send().await?.error_for_status()?;

              let res_url = resp.url().to_string();

              // TODO(andreubotella) Properly run fetch's "extract a MIME type".
              let mime_type = resp
                .headers()
                .get("Content-Type")
                .and_then(|v| v.to_str().ok())
                .map(mime_type_essence);

              // Always check the MIME type with HTTP(S).
              loose_mime_checks = false;

              let body = resp.bytes().await?;

              (body, mime_type, res_url)
            }
            "data" => {
              let data_url = DataUrl::process(&script)
                .map_err(|e| type_error(format!("{e:?}")))?;

              let mime_type = {
                let mime = data_url.mime_type();
                format!("{}/{}", mime.type_, mime.subtype)
              };

              let (body, _) = data_url
                .decode_to_vec()
                .map_err(|e| type_error(format!("{e:?}")))?;

              (Bytes::from(body), Some(mime_type), script)
            }
            "blob" => {
              let blob =
                blob_store.get_object_url(script_url).ok_or_else(|| {
                  type_error("Blob for the given URL not found.")
                })?;

              let mime_type = mime_type_essence(&blob.media_type);

              let body = blob.read_all().await?;

              (Bytes::from(body), Some(mime_type), script)
            }
            _ => {
              return Err(type_error(format!(
                "Classic scripts with scheme {}: are not supported in workers.",
                script_url.scheme()
              )))
            }
          };

          if !loose_mime_checks {
            // TODO(andreubotella) Check properly for a Javascript MIME type.
            match mime_type.as_deref() {
              Some("application/javascript" | "text/javascript") => {}
              Some(mime_type) => {
                return Err(
                  DomExceptionNetworkError {
                    msg: format!("Invalid MIME type {mime_type:?}."),
                  }
                  .into(),
                )
              }
              None => {
                return Err(
                  DomExceptionNetworkError::new("Missing MIME type.").into(),
                )
              }
            }
          }

          let (text, _) = encoding_rs::UTF_8.decode_with_bom_removal(&body);

          Ok(SyncFetchScript {
            url: res_url,
            script: text.into_owned(),
          })
        })
      })
      .collect();

    let mut ret = Vec::with_capacity(handles.len());
    for handle in handles {
      let script = runtime.block_on(handle)??;
      ret.push(script);
    }
    Ok(ret)
  });

  thread.join().unwrap()
}